Weather it is driven by local code, or it is more of a formal decision on the part of an architect, I am not sure, but the clear expression of the stairs (fire escape I assume) is a reoccurring theme on Tokyo's streetscape. The staircase often occupies a large portion of the street facade, which in many cases is the only visible facade, since many buildings are tightly 'packed' together with barely a foot or two between. But unlike the 'typical' utilitarian staircases of tall buildings in US cities (I have a vivid image of Chicago's rusty metal staircases in my mind), Tokyo's staircases are sculptural, many times with great detailing, and are either fully integrated into the rest of the building's facade or clearly stand out on their own.